Andy Murray endured a difficult 2014 and will be hoping his form improves next year. Photograph: Adam Davy/PA

Andy Murray has signed a four-year kit deal with the US-based sportswear company Under Armour believed to be worth in the region of £15m.

The 2013 Wimbledon champion will wear Under Armour’s apparel, footwear and accessories during competitions and will feature in marketing campaigns for the company, which is based in Baltimore.

“I am very honoured and excited to be joining Team Under Armour and to help them tell their story globally,” Murray said. “They are committed to providing innovative apparel, accessories, and footwear, with an unmatched focus on training and performance.”

Murray previously had a sponsorship deal with Adidas, which is believed to have been worth £15m over five years.

Other athletes who are contracted to Under Armour include Tom Brady, Jordan Speith and Lindsey Vonn.